<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			*{
				margin:0;
				padding:0;
				list-style: none;
			}
			ul{
				width:600px;
				height:32px;
				border:1px solid red;
				margin:0 auto;
			}
			ul li{
				height:32px;
				width:80px;
				text-align: center;
				line-height: 32px;
				float:left;
				border-right: 1px solid red;
			}
			ul .c3{
				/*清除浮动:clear  left right both*/
				/*clear:left;
				clear:right;*/
				clear:both;
			}
			ul .c4{
				clear:left;
			}
		</style>
	</head>
	<body>
		<ul>
			<li>1</li>
			<li>2</li>
			<li class="c3">3</li>
			<li class="c4">4</li>
		</ul>
	</body>
</html>
